Rover - Skid Steer Servo with spring center controls

Folks, I know this will be simple answer for some, but I have been banging my head on this one.
I want to control two servos for both right/left turn and forward/reverse. That is, push the stick forward in the center the rover travels forwards and when the stick is pushed to the left while full forward, the left motor will begin moving to reverse. If is have the stick center vertically and push to the left, left motor full revers and right motor full forward. Skid steer with forward and revers motion on a single stick. I am not using motors, but servos.
Using Pixhawk 2.4.8, Mission Planner ArduPilort

Any help would be appreciated.